Process for making copper soaps



I 1 these by the generally applicable procedure of mixing an aqueoussolution of the corresponding renal 194a I uni-re STATES PATENT orr cs 72,391,101 f corporation of Ohio No. Drawing. Application October 4,1943, Serial s Claims. (01. zoo-414) This invention relates to a methodof preparing copper saltsof higherfatty acids.

More particularly, it relates to a method of making copper soaps bydirect action of fatty acids'and metallic corn ess for making coppersoaps which, if desired, are substantially free from oleaginousimpurities.

' per soaps. A further object is toprovide a proc- Heretofore, whenoil-free or fatty-acid-free soaps of bivalent or trivalent metals havebeen needed, it has been common practice to prepare sodium or potassiumsoaps with an aqueous solution of a water soluble salt of the metal.Thus copper soaps of -oleic acid may, for example, be prepared by mixingequivalent amounts of aqueous solutions of sodium-cleats and of coppersulfate. This procedure. while convenient for laboratory practice, isnot particularly suitable for large scale commercial preparation ofcopper soaps, especially when a water free product is required. Itnecessitates a number of separate steps which it is one of my objects toavoid. It produces wet soaps which, due to their soft and sticky nature,are dimcult to dry.

is suitable for employment in the commercial manufacture of coppersoaps.

. In the process of my invention, when carried out in a preferredmanner, 1 heat the selected fatty acids to a temperature in theneighborhood of 200 C., add an equivalent amount of comminuted copper(assuming that cupric soaps will be formed) agitate this slurrythoroughly while maintaining its temperature at about 200 C., and blowair through the mixture at a rapid rate. Under these conditions I findthat the copper dis- 7 solves completely and rapidly to produce a moltenmass of dry cupric soaps of good quality, which are substantiallyuncontaminated with free fatty acids. It is desirable to discontinue theair blowing as soon as the reaction is complete, s Judged by thecomplete dissolution of the copper .or by. chemical analysis or otherconvenient means, and then either to cool the molten soaps or to protectas them from further contact with air.

When this same procedure is followed with the omission of air blowing,the reaction is entirely too slow and incomplete to be of any commercialinterest. In the absence of air blowing, only as about'one tenth of thecopper goes into solution Iadd 318 pounds of powderedcopper to 2090 inthe time required to complete the reaction according to my process.

As an example of the process of my invention,

pounds of the mixed fatty acids vderived from coconut oil, stir thisslurry vigorously by means of a mechanical agitator while maintainingits temperature at about 200 C., and blow a vigorous current of airthrough the mixture until the cop- An object of my invention is toprepare dry per is dissolved. 'I'hisusuall requires about one copper,soaps, which may be substantially free from oleaginous impurities, by adirect single stage procedure. thus avoiding the multiplicity of stepsinherent in the double decomposition method heretofore commonly used.

It has been known that metallic copper is attacked by higher fattyacids, and that copper soaps are formed as a result. when melted stearicacid is held for some time in a copper vessel, it is known that thestearic acid develops a greenish color as a result of dissolving smalltraces of copper. This action is so slow, however, that it does notdeter the widespread use of copper equipment in the industrial handlingof hot fatty acids. Copper tanks used for storing fattyacids and copperpipes through which hot fatty acids are pumped last for many years inthis service.

An object of my invention is to provide a process for reacting metalliccopper with higher fatty to one and a half hours. I then shutoff the airand transfer the resulting molten copper soaps to a storage tank whichmay, if desired, be blanketed with nitrogen to avoid unnecessar oxida-40 tion of the product.'

At the temperature employed in my process, a

certain amount of distillation of fatty acids, especially those of lowermolecular weight, is found to occur. To prevent this loss, it isdesirable to lead the outgoing air through a reflux condenser whichdrains back into the reaction vessel, or alternatively to start withsomewhat more than an equivalent amount of fatty acids to compensate forthe distillation loss.-

Copper soaps of any of the higher fatty acids may be prepared by thisprocess. Such fatty acids may be derived from any of'the naturallyoccurring fats or glyceride oils, or from waxes or resins, or may beprepared synthetically, as by acids, which is so rapid and so economicalthat it 66 the catalytic oxidation of petroleum. These fatty acids,which may contain eight or more carbon atoms in the molecule, and morecommonly from twelve to twenty-two. may be saturated or unsaturated,either hydrogenated or unhydrogenated.

A reasonable latitude in the temperature employed in the process ispermissible. I flnd that the reaction occurs undesirably slowly attemperatures as low as 100 C. Prolonged blowing with air, as is requiredwhen the reaction occurs slowly, is to be avoided because of thetendency of the fatty acids and soaps to become oxidized and todecompose. For a like reason, i. e., the avoidance of excessiveoxidation, temperatures greatly in excess of 200 C. are to be avoided.Accordingly I prefer to conduct my process within the range of 125- C.to"245 0., and I particularly recommend the narrower range of 170 C.

to 220 C.

Mechanical agitation is usually helpful, unless a large excess oi copperis employed, because copper is so dense that it tends to settle rapidly.Very good gas agitation may, however, be substituted with satisfactoryresults.

Although air is the most convenient oxidizing gas to use. and is quitesuitable, other oxygencontaining gases including pure oxygen may besubstituted. In this connection the term oxygen-containing gas denotes agas containing free molecular oxygen.

As a source of metallic copper for my process, I prefer comminutedcopper, such as is formed when copper soaps are subjected to reactionwith hydrogen at elevated temperature and pressure, althoughmechanically powdered copper such as copper filings may be used. Evencopper turnings or other forms of copper having a large spams? son andTaylor, now U. 8. Patents Nos. 2,840,343 and 2,340,344, issuedFebruary 1. 1944. When 1 the copper soap of a higher fatty acid issubiected to reaction with molecular hydrogen at quite high temperaturesand pressures, the free metal is liberated and a higher fatty alcohol isformed. In the commercial practice of this process it is highlydesirable to reuse the resulting freecopper in the preparation ofanother lot of copper soaps for reduction to another lot of alcohols.Copper soaps produced by my process from copper precipitated in thisalcohol manufacturing procedure are found to reduce readily areadvantageously incorporated.

' Having thus described my invention, what I claim and desire to secureby Letters Patent is: 1. The improvement in processes for forming I thecupric soap of a higher fatty acid, which surface per unit of mass, ifused in sufficient excess, may be employed, and these are to beconsidered as coming within the scope of my invention.

Although I prefer to employ substantially,

equivalent proportions of fatty acid and copper, my process is notlimited to such proportions. At times a mixture consisting of coppersoaps and free fatty acids may be desirable (or at leastunobjectionable) as the final product, and in such cases an excess offatty acids may be employed in the process. At other times there may beno objection to having free copper in the scans produced by the process,and in this event the reaction time-may be reduced by employing anexcess of finely divided copper in the reaction mixture.

My procesgis particularly applicable and desirable in the preparation ofcopper soaps for reduction to fatty alcohols by the method described inapplications Ber. Nos. 370,072 and 370,073, filed on February 21, 1941,by Richardcomprises mixing said fatty acid with comminuted copper andblowing an excess of an oxygen-containing gas through said mixture whilethe latter is at a temperature between 125 C. and 245 C.

2. The process of claim 1, in which substantially equivalent amounts offatty acid and copper are employed.

3. The process of claim 1, in which mechanical agitation is employed topromote contact between the reactants.

4. The process of claim 1, in which said fatty 0 acid is derived fromcoconut oil.

5. The process of claim 1, in which the temperature is held within therange of 170 C. to

I 0. and 245 0.

JAMES E. TAYLOR.

